OpenDaylight beams down a little Hydrogen

First code release offers SDN and network function virtualisation

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The Linux foundation's hat-in-the-SDN-ring, the OpenDaylight project, has pushed its first major build out the door: Hydrogen, a combo software-defined networking (SDN) and network function virtualisation (NFV) platform.

With code now hitting the ground, OpenDaylight has also gone some way towards one of its original aims: to be the reference implementation of SDN into the future. While Hydrogen is still a first release, it achieves the “data plane versus control plane” split that's fundamental to SDN – and means that within the ambit of Hydrogen, there will be a lot of scope to take its open source APIs and add more capable software.

Its basic architecture is simple: the Hydrogen SDN controller exposes APIs upwards to the outside world; while plugins beneath the controller communicate with the networking hardware. The plug-in model means that vendors can talk to the controller without Hydrogen users having to get their heads around a mass of different vendor APIs.

There are three editions of Hydrogen: an entry level base edition, the Virtualization Edition, and the Service Provider Edition.

Here's the OpenDaylight summary of each edition:

Base Edition – an OSGi-based modular SDN controller; an OpenFlow plug-in that integrates the OpenFlow library (version 1.3) with the controller's service abstraction layer (SAL); support for the Open vSwitch Database config / management tool; and the Java-based NETCONF and YANG tools.

Service Provider Edition – “All of the above”, plus support for traffic engineering in BGP-LS and PCEP; Locator/Identifier Separation Protocol (LISP) support; and an SNMP implementation, SNMP4SDN, to manage Ethernet kit.

All the releases will run under Fedora 20 or Ubuntu Test VMs.

There's plenty of big name support for OpenDaylight and Hydrogen – the platinum sponsor list alone ticks off Cisco, Brocade, Citrix, Ericsson, IBM, Juniper Networks, Microsoft and Red Hat. However, in a lot of ways, SDN is still an embryonic creature.

The separation of control plane and data plane in big networking kit is nothing new: pretty much as soon as switches and routers got too big to fit in a single box, it occurred to vendors that this was a requirement.

However, the interaction between the two has hitherto been proprietary. The sysadmin gets access to the management interface of the control plane, and the vendor alone decides how the control plane talks to the data plane.

In Hydrogen, the service abstraction layer isolates the plugins that communicate with switches and routers – the southbound forwarding elements, in OpenDaylight-speak – from the APIs that face northward, on which management and control applications will be built.

It's worth noting that even in this "open" world, OpenDaylight has still faced accusations of being dragged into the orbit of big vendors. Last year, BigSwitch quit the group accusing it of favouring Cisco's code contributions. ®